GREENSBORO, N.C. -- Maryland had the energy, and the Terrapins had Dez Wells.

It was the right combination to knock off second-ranked Duke on Friday night.

Wells scored 30 points while the Blue Devils suffered through a miserable shooting performance from the perimeter, allowing the Terrapins to pull off an 83-74 stunner in the Atlantic Coast Conference tournament quarterfinals at the Greensboro Coliseum.

"I'm trying to be an energy guy for this team," Wells said. "I just wanted to get my guys energized."

Duke had no match for that, something coach Mike Krzyzewski noticed right away.

"We didn't play like it was one-and-done tonight," Krzyzewski said. "They did, and they won. They were the hungry team. I didn't think we were hungry. (Maryland is) trying to survive, and they played like that. They were superb."

Maryland (22-11) will play in Saturday afternoon's second semifinal against the winner of Friday's Florida State-North Carolina game.

Seventh-seeded Maryland, which probably has to win the ACC tournament to land a spot in the NCAA Tournament, never trailed against Duke (27-5).

The Terrapins were strong from the get-go.

"Watching them play, I think they fully expected to win this game," Maryland coach Mark Turgeon said of his players.

Wells, who's in his first season with the team after transferring from Xavier, was the aggressor early on and again down the stretch.

"First, I had to figure out how to coach Dez," Turgeon said. "We knew Dez was a big-time player. Tonight was a big-time performance for him."

Wells, a sophomore guard, scored 21 points Thursday in a victory against Wake Forest. He picked up where he left off the next night.

"He has elevated himself to a really high level, and you can bring everyone with you," Krzyzewski said of Wells.

Four other Maryland players -- Nick Faust, Alex Len, Jake Layman and Seth Allen -- scored 10 points each.

Mason Plumlee scored 19 points to pace Duke, which shot 4-for-25 on 3-point attempts. Rasheed Sulaimon added 16, and Seth Curry had 15.

Duke's quest to land a No. 1 regional seed for the NCAA Tournament could be damaged even though it won five of its last six regular-season games after losing Feb. 16 at Maryland. Four of those victories were by double-digit margins, and the other came against ACC regular-season champion Miami.

"I don't see any positive right now," Curry said. "We wanted to come into this tournament and play well. We took a step back. ... We need to be sharper. We need to play a lot harder from the start."

Maryland scored five of the first seven points in the second half to lead 39-28. A four-point play by Curry ignited an 8-2 run, causing Maryland to call timeout.

Duke was within 45-44 on Ryan Kelly's three-point play before the Terrapins took off again, cranking their lead to 65-52 with less than six minutes to play.

"They seemed to always have an answer," Plumlee said. "That's what prevented us from getting back."

The Blue Devils were within 67-60 with four minutes to play. Wells scored Maryland's next four points.

Duke fell to 17-1 all-time against the tournament's No. 7 seed.

Turgeon, who pointed out that the second victory of the season against Duke is bound to be good for his relationship with his fan base, said he thinks the Terrapins pounced on opportunities in the opening minutes.

"They missed some shots for us," Turgeon said. "I think our press kind of confused them early. ... I think pressing early kind of got us going. We got confident."